Immunological Evaluation Of Rabies Vaccine With Emulsion Adjuvant Comprise Salmonella Paratyphi A

Rabies is a zoonotic virus which cause 55,000 people worldwide die every year.Most of them come from developing countries such as China,India and Pakistan.Rabies vaccination is a key to prevent rabies,but the immunization program needs to be injected 4-5 times within 28 days.The human diploid rabies vaccine has low side effects and great immunogenicityis but facing an dilemma which is expensive and undercapacity.Rabies vaccine without adjuvant,the neutralizing antibody titer reach the effective protection level needs at least 14 days,which can’t meet the need of exposer to produce protective neutralizing antibodies as soon as possible.Use of adjuvant can effectively reduce the dose of rabies vaccine and enhance immunity,product neutralizing antibodies early,research rabies vaccine adjuvants have important implications for the control of rabies.Salmonella paratyphi A flagellin is a structural component of flagella.It is recognized as a TLR5 agonist.The flagellin is mixed with or expressed in antigent that a variety of vaccine have been used.TLR5 is located on the surface of various immune cells and can trigger the secretion of inflammatory factor chemokines,cytokine and initiates innate immune response.Recruits T and B lymphocytes to the lymphoid organs to promote activation of APC and enhance cellular and humoral immune responses.In this study,squalene,span,tween,and salmonella paratyphi A flagellin were used to prepare for composite emulsion adjuvant with an average particle size of about 187 nm.This adjuvant can accelerate the production of neutralizing antibodies and enhance specific immunity and nonspecific immunity.The rapid fluorescent focus inhibition test showed that the neutralizing antibody was higher than 0.5 IU/ml on the 7th after the first injection and the neutralizing antibody(1.0 IU/ml)of the medium dose of salmonella paratyphi A flagellin emulsion adjuvant was significantly higher than the full dose vaccine group(0.38 IU/ml),and the neutralizing antibody reached 3.8 IU/ml in 14th day higher than full-dose vaccine group(2.2 IU/ml).The number of lymphocytes secreting IFN-y and IL-4 in mice infected with the adjuvant was significantly increased.The expression immunochemokines MCP-1 and MIP-la mRNA was up-regulated at the injection site after immunization and 6 h reached the peak.In the challenge trial,the survival rate of the salmonella paratyphi A flagellin was 100%.No significant difference in the pathological sections of the heart,liver,spleen.lung and kidney of the mice compare with the vaccine control group proved that the adjuvant was safe.The mouse model imitate the natural infection was used to invest the protection of adjuvant for PEP and the survival rate of intramuscular injection and intradermal injection was higher than that of the non-adjuvant group.The effect of internal immunization is optimal and the antigen dosage can be significantly reduced.In summary,the adjuvant can effectively reduce the dose of rabies vaccine with safety and immunogenicity.